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.\" Author: Jan Glauber <jang@linux.vnet.ibm.com>
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.TH S390_RUNTIME_INSTR 2 2012-12-17 "Linux Programmer's Manual"
.SH NAME
s390_runtime_instr \- enable/disable s390 CPU run-time instrumentation
.SH SYNOPSIS
.nf
.B #include <asm/runtime_instr.h>

.BI "int s390_runtime_instr(int " command ", int " signum ");
.fi
.SH DESCRIPTION
The
.BR s390_runtime_instr ()
system call starts or stops CPU run-time instrumentation for the
calling thread.

The
.IR command
argument controls whether run-time instrumentation is started
.RB ( S390_RUNTIME_INSTR_START ,
1) or stopped
.RB ( S390_RUNTIME_INSTR_STOP ,
2) for the calling thread.

The
.IR signum
argument specifies the number of a real-time signal.
The real-time signal is sent to the thread if the run-time instrumentation
buffer is full or if the run-time-instrumentation-halted interrupt
occurred.
.SH RETURN VALUE
On success,
.BR s390_runtime_instr ()
returns 0 and enables the thread for
run-time instrumentation by assigning the thread a default run-time
instrumentation control block.
The caller can then read and modify the control block and start the run-time
instrumentation.
On error, \-1 is returned and
.IR errno
is set to one of the error codes listed below.
.SH ERRORS
.TP
.B EINVAL
The value specified in
.IR command
is not a valid command or the value specified in
.IR signum
is not a real-time signal number.
.TP
.B ENOMEM
Allocating memory for the run-time instrumentation control block failed.
.TP
.B EOPNOTSUPP
The run-time instrumentation facility is not available.
.SH VERSIONS
This system call is available since Linux 3.7.
.SH CONFORMING TO
This Linux-specific system call is available only on the s390 architecture.
The run-time instrumentation facility is available beginning with System z EC12.
.SH NOTES
Glibc does not provide a wrapper for this system call, use
.BR syscall (2)
to call it.
.SH SEE ALSO
.BR syscall (2),
.BR signal (7)
